Confused about calorie deficit needed for 1kg weight loss and MFP calculations
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Lietchi
Posts: 6,128 Member
So I’ve been tracking my weight, my calories in and out, my deficit, etc. in an Excel file. And I noticed something isn’t adding up.
My own calculations are based on the info that I’ve seen online, saying that a 7700 kcal deficit equals (more or less) losing one kg of bodyfat (3500kcal per lb).
So I presumed that MFP uses that number to calculate the deficit we need to lose at the rate we chose in the settings. In my case that’s 0.25 kg per week, which would mean a daily deficit of 275 calories.
I picked some dates from my MFP log and calculated the deficit goal MFP gave me:
Am I missing something in my calculations? Or is MFP using a different formula?
My main concern is trying to determine if I burn more or less calories than expected, so I’d like to use a correct formula for the deficit needed to lose 1kg of bodyfat.
PS: yes, I am a data geek
My own calculations are based on the info that I’ve seen online, saying that a 7700 kcal deficit equals (more or less) losing one kg of bodyfat (3500kcal per lb).
So I presumed that MFP uses that number to calculate the deficit we need to lose at the rate we chose in the settings. In my case that’s 0.25 kg per week, which would mean a daily deficit of 275 calories.
I picked some dates from my MFP log and calculated the deficit goal MFP gave me:
- my total calories burnt based on the adjustment through my fitness tracker (steps and exercice)
- MINUS the calories of food I logged
- MINUS the number of calories MFP tells me I have left at the end of the day
Am I missing something in my calculations? Or is MFP using a different formula?
My main concern is trying to determine if I burn more or less calories than expected, so I’d like to use a correct formula for the deficit needed to lose 1kg of bodyfat.
PS: yes, I am a data geek
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Replies
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I'm not 100% sure, but I *think* you're seeing the synchronization rate of your fitness tracker adjustments to MFP, which will play tug of war with equations and try to get you roughly centered, but unless your burn is absolutely perfectly metered to the expectations of both (nearly impossible) there is going to be some play in the data depending on the part of the day wherein the snapshot is captured.3
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MFP runs the numbers from one end and your tracker runs numbers from the other, and they *try* to meet in the middle, but the "middle" will vary based on meal timing relative to your exercise calories burned. The tracker thinks it has your "real time" burn, but doesn't get your meals until you log them into MFP - if it even gets them at all. MFP doesn't get your burn until the tracker reports, and sometimes the report doesn't come in until after you've finished eating for the day.0
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You have exercise showing in your diary, so MFP is designed such that any calories burned during exercise will be eaten back and automatically added to your calorie goal. I don't have any devices that sync to MFP, but I assume if you do then your exercise may be automatically logging.
There's a setting for "Enable Negative Adjustments" that also fiddles with you daily calories which you can turn off under the diary settings.1 -
I am a little confused by your post. If you told MFP you want to lose 0.25kg a week, it will factor that into your goal already. So if it tells you your goal is 1700 calories, you eat all 1700, not 1700-275. If you sync a fitness tracker, your goal will vary every day based on your activity level. but it will incorporate the deficit you choose.
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To clarify: I'm only looking at the data registered in the MFP app (directly or synced via activity tracker) and I only looked at completed days (so all meals entered and all burnt calories fully synced between my activity tracker and MFP).ElizabethKalmbach wrote: »MFP runs the numbers from one end and your tracker runs numbers from the other, and they *try* to meet in the middle, but the "middle" will vary based on meal timing relative to your exercise calories burned. The tracker thinks it has your "real time" burn, but doesn't get your meals until you log them into MFP - if it even gets them at all. MFP doesn't get your burn until the tracker reports, and sometimes the report doesn't come in until after you've finished eating for the day.
I'm not talking about the calorie goal, I understand how that works. I'm asking about the deficit MFP uses to calculate that calorie goal: the number of calories MFP calculates to arrive at a a certain weightloss rate.I am a little confused by your post. If you told MFP you want to lose 0.25kg a week, it will factor that into your goal already. So if it tells you your goal is 1700 calories, you eat all 1700, not 1700-275. If you sync a fitness tracker, your goal will vary every day based on your activity level. but it will incorporate the deficit you choose.
MFP's calorie goal for the day = number of calories for weight maintenance (NEAT +exercise) - deficit needed for set weight loss rate
It's this last number that I'm wondering about, how MFP arrives at this number. Seemingly not by simply counting 7700kcals=1kg bodyfat, unless I'm missing something.0 -
If you checkin your weight, it also alters the math, lower body weights will calculate out to slightly lower NEAT values, so that would reduce your goal calories even if the deficit is the same, right?0
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tcunbeliever wrote: »If you checkin your weight, it also alters the math, lower body weights will calculate out to slightly lower NEAT values, so that would reduce your goal calories even if the deficit is the same, right?
In theory yes, the NEAT should go down as the weight goes down. That is precisely why I have my own Excel file with my own calculations, because MFP does NOT adapt my NEAT unless I explicitly 'adapt' (confirm) my goals in the settings.
But it is not relevant for my question actually: I'd like to know how MFP determines the amount of calories I should be in deficit, and if for my own Excel file I should simply use 7700kcal=1kg fat or maybe there is something better.0 -
To clarify: I'm only looking at the data registered in the MFP app (directly or synced via activity tracker) and I only looked at completed days (so all meals entered and all burnt calories fully synced between my activity tracker and MFP).ElizabethKalmbach wrote: »MFP runs the numbers from one end and your tracker runs numbers from the other, and they *try* to meet in the middle, but the "middle" will vary based on meal timing relative to your exercise calories burned. The tracker thinks it has your "real time" burn, but doesn't get your meals until you log them into MFP - if it even gets them at all. MFP doesn't get your burn until the tracker reports, and sometimes the report doesn't come in until after you've finished eating for the day.
I'm not talking about the calorie goal, I understand how that works. I'm asking about the deficit MFP uses to calculate that calorie goal: the number of calories MFP calculates to arrive at a a certain weightloss rate.I am a little confused by your post. If you told MFP you want to lose 0.25kg a week, it will factor that into your goal already. So if it tells you your goal is 1700 calories, you eat all 1700, not 1700-275. If you sync a fitness tracker, your goal will vary every day based on your activity level. but it will incorporate the deficit you choose.
MFP's calorie goal for the day = number of calories for weight maintenance (NEAT +exercise) - deficit needed for set weight loss rate
It's this last number that I'm wondering about, how MFP arrives at this number. Seemingly not by simply counting 7700kcals=1kg bodyfat, unless I'm missing something.
The deficit number is set.
Obviously the starting number changes using an tracker allowing MFP to correct itself.
But, MFP has a base level of 1200 women and 1500 men it won't go below.
And then exercise is added after, which includes the tracker adjustment.
So you are looking at daily numbers and doing the math the wrong direction.
MFP estimated base calorie burn - you can find this in your Goals page.
Minus deficit also should be shown on Goals page.
Base eating goal not less that 1200 or 1500 daily eating goal though.
Base goal plus the total exercise calories is new eating goal.
Exercise calories is any manually logged exercise (but really should let the tracker do that part), plus any tracker adjustments, which could be negative if that setting is enabled.
With minimal deficit you really shouldn't hit the floor normally - but could if short/small/older ect your Sedentary level could be small if set to that.
If you normally get big adjustments positive from tracker, might think about raising base activity level, which would allow full deficit to be taken.
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The deficit number is set.
This is my question. How is it set? In the goal settings it only says at which rate you want to lose weight, not to how many calories of deficit per day this equates.
To give a very concrete example, my diary for yesterday:
For calories OUT: I effectively burned 2398kcal (specified in the MFP app where it mentions the calorie adjustment from my activity tracker)
For calories IN:
- effectively consumed/logged calories: 2004
- calories remaining = 96
=> so total number of calories MFP wanted me to consume = 2100
Conclusion: MFP wanted me to have a deficit of 2398 minus 2100 = 298 kcal
Which is a strange number, not the 275 kcal per day I was expecting based on 7700kcal/kg bodyfat.
And this number varies from day to day: same calculation for Tuesday gives 288 kcal as a result, for example.
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MFP is giving you a base 1660 calories every day, then adding in calories for your exercise and your Polar each day.
Yesterday your polar adjustment was 215.
You also walked for an additional 225
that makes your total goal 2,100
I'm not aware of any place where MFP tells you what it calculates your calorie burn as...but I'm on the desktop and I'm not syncing a device, so maybe that's why I don't see that information.0 -
tcunbeliever wrote: »I'm not aware of any place where MFP tells you what it calculates your calorie burn as...but I'm on the desktop and I'm not syncing a device, so maybe that's why I don't see that information.
Only people who have an activity tracker synced see this info, I think.
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Ah, that's really cool!!!0
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To check what MFP is using for your estimated daily burn - go into your settings and change to maintenance.
At end of that process it shows your daily goals - there's your eating goal.
That's maintenance level, so that's your estimated daily burn. (but indeed with a tracker adjustment you see it too - 1958 currently)
Now change the setting to desired deficit again.
There's eating goal again, now you know the deficit.
Now the kicker is your prior info to the above process may have been based on prior weight if you've lost any.
The daily burn estimate is lowered as your new weight is input, but the eating goal isn't lowered until 10 lbs go off (or whatever matches close kg).
The daily burn that changes based on weight is used with math with tracker.
Tracker calories - MFP estimated daily burn - logged exercise = adjustment.
base eating goal + logged exercise + adjustment = new eating goal.
Tracker 2398 - 1958 MFP - 225 = 215
1660 base eating + 225 exercise + 215 adjustment = 2100
1958 - 1660 = 298 deficit indeed.
Do you update daily weight fluctuations?0 -
I don't use the MFP generated deficit values, I carb/calorie cycle, so I set mine up as custom and I have an "offset" value that I key for my lower carb/calorie days.
I do try to track weight and such daily, but I'm terrible about remembering to get on the scale, and MFP doesn't adjust custom settings with weight changes. It will still adjust for exercise, so I just don't key activity, or if I key it I set calories to "1" so that it doesn't mess up my calorie goals.
It's very interesting to know how MFP does the math, particularly with the addition of the monitoring device.
It does seem weird that it's not consistent, though I guess 10 calories over or under is not a huge amount, but you would think the math would be the same all the time.0 -
As you've noted the eating goal doesn't change on manual entry, nor on initial goal set by MFP.
Weight must lower by 10 lbs for it to auto-ask if you want to adjust. (and even there ones have commented it did not for them)
But the daily burn estimate is based on current entered weight and changes.
And that potentially variable number is used for the math with a tracker, besides the tracker adjustment showing what it currently is.
So changing number is possible.0 -
Thanks for the replies, it seems the mystery has been solved!
I find it slightly bizarre that MFP adapts the estimated calorie burn from day to day (taking into account weight changes) but doesn't update the calorie intake goal to those same weight changes.
But it is what it is, I'm even more motivated now to keep on updating my own Excel file with my own calculations
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Well, changing the eating goal each day based on someone making normal fluctuating 1-3 lb changes would be a little annoying for those that like to get a number down.
If you do the math, it takes about 10 lb loss to change the eating level enough to really matter in the scheme of things.
Something I'm also wondering about is if the eating goal was ever tweaked at some point, I'll bet the whole auto-process is disabled.
So if MFP originally said eating goal 1657 and someone made it even 1600 just because - off it comes from auto-updates.
Or the app isn't good at presenting question to user if they want to update eating goal, or it looks like something else and just swiped away.
I could see several reasons why the auto doesn't occur.
But for trackers that are using constantly different values, no problem if MFP is for estimated daily burn.0 -
I had already lost 12 lbs when I was, by chance, 'tinkering' with my goals (opening the different options and then confirming my existing goals) and then suddenly my calorie goal dropped 80kcal per day.
It might not seem like much, but in my case I'm aiming at .5lb of weight loss per week, 80kcal is considerable for a deficit goal of 275kcal.
Definitely something wrong with this automatic update after 10lbs weight loss, at least for me, I'm sure I wasn't prompted for anything (I'm not even receiving ordinary notifications on comments etc on my newsfeed, but that's another issue). And I never set my calories manually either. I'm just glad I noticed the issue in time before my weight loss stalled and now I keep an eye on it. We live, we learn!0
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